西藏珠穆朗玛峰北坡地区显生宙沉积演化

位于印度板块北缘和雅鲁藏布江结合带之间的珠穆朗玛峰北坡地区，属于喜马拉雅造山带，是特提斯洋的重要组成部分。自奥陶纪至古近纪约5亿年期间发育一套基本连续的海相沉积，厚度达14 km，是研究特提斯洋形成演化的最佳地区。作者在对该区显生宙地层主干剖面和辅助剖面详细观察研究以及区域地质调查填图的基础上，将珠穆朗玛峰北坡地区显生宙沉积地层划分为海相、海陆过渡相和陆相3个沉积相组、15个沉积相和若干个沉积亚相。作者通过对该区沉积盆地的地层系统、沉积相、沉积特征的系统研究，将珠穆朗玛峰北坡地区显生宙沉积演化划分为6个阶段:1)奥陶纪-泥盆纪为稳定陆表海演化阶段；2)石炭纪-二叠纪为大陆裂谷盆地演化阶段；3)三叠纪-侏罗纪为被动大陆边缘盆地演化阶段；4)早中白垩世为前陆早期复理石盆地演化阶段；5)晚白垩世-古新世为前陆晚期磨拉石盆地演化阶段；6)古近纪-第四纪为造山隆升断陷盆地形成演化阶段。研究结果表明，珠穆朗玛峰北坡地区显生宙沉积盆地经历了由陆表海盆地-大陆裂谷盆地-被动大陆边缘盆地-前陆盆地-断陷盆地的演化过程。

Sedimentary evolution of the Phanerozoic of north slope area of Mount Qomolangma, Tibet

The north slope area of the Mount Qomolangma being a main component of Tethyan Ocean belongs to Himalayan orogen intermediate on the junction between the northern India plate and Yarlung Zangbo river suture belt. There developed basic unharmed marine strata being about 14 000 m in thickness during about 50 million years from the Ordovician to the Paleogene. It is a good area for studying the formation and evolution of the Tethyan Ocean.The Phanerozoic strata in the north slope area of the Mount Qomolangma are made up of three sedimentary facies sets and 15 sedimentary facies and many subfacies. Based on the characteristics of the basin stratigraphic sequences,the depositional systems and the sedimentary facies,the sedimentary-tectonic evolution of the basin in Phanerozoic may be subdivided into six stages for the north slope area of the Mount Qomolangma,Tibet.(1)the steady epicontinental sea stage from Ordovician to Devonian;(2)the continental rifting basin stage from Carboniferous to Permian;(3)the passive continental margin stage from Triassic to Jurassic;(4)the early foreland flysch basin development stage in the Early-Middle Cretaceous;(5)the late foreland molasse basin development stage from the Late Cretaceous to the Paleocene;(6)the orogenic uplifting stage from the Paleogene to the Quaternary.